RosettaCodeData/Task/Rosetta-Code-Rank-languages-by-popularity/C/rosetta-code-rank-languages-by-popularity-2.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include "cJSON.h"
char *URL_BASE = "http://www.rosettacode.org/mw/api.php?format=json&action=query&generator=categorymembers&gcmtitle=Category:Programming%20Languages&gcmlimit=500&prop=categoryinfo&rawcontinue";
char *URL_BASE_CONT = "http://www.rosettacode.org/mw/api.php?format=json&action=query&generator=categorymembers&gcmtitle=Category:Programming%20Languages&gcmlimit=500&prop=categoryinfo&gcmcontinue=";

typedef struct mem {
  char *text;
  size_t size;
} mem;

typedef struct page {
  char *name;
  int num;
} page;

size_t write_callback(void *ptr, size_t size, size_t nmemb, void *userdata);
void curl_request(CURL *curl, char *url, mem *response);
char *build_url(char *cont);
char *get_cont(cJSON *json);
void sort_arrays(page *pages, int *s);
cJSON *parse_json(cJSON *json);
page *fill_arrays(page *pages, int *s, cJSON *json);

int main(int argc, char *argv[]) {
  curl_global_init(CURL_GLOBAL_ALL);
  CURL *curl = curl_easy_init();
  char *cont = NULL;
  page *pages = malloc(1);
  int till = 10;
  int *npag = malloc(sizeof(int));
  *npag = 0;
  if (argc>1) till = atoi(argv[1]);
  do {
    mem *response = calloc(1, sizeof(mem));
    char *url = build_url(cont);
    if (cont) free(cont);
    curl_request(curl, url, response);
    cJSON *json = cJSON_Parse(response->text);
    cont = get_cont(json);
    cJSON *json_pages = parse_json(json);
    pages = fill_arrays(pages, npag, json_pages);
    cJSON_Delete(json);
    free(url);
    free(response->text);
    free(response);
  } while (cont);
  sort_arrays(pages, npag);
  if (till>*npag||till<-1) till=10;
  if (till==-1) till=*npag;
  for (int i = 0;i<till;i++) {
    printf("#%d: %s, %d tasks\n", i+1, pages[i].name, pages[i].num);
  }
  for (int i = 0;i<*npag;i++) {
    free(pages[i].name);
  }
  free(pages);
  free(npag);
  curl_easy_cleanup(curl);
  curl_global_cleanup();
  return 0;
}
size_t write_callback(void *ptr, size_t size, size_t nmemb, void *userdata) {
  mem *response = userdata;
  response->text = realloc(response->text, response->size+size*nmemb+1);
  memcpy(&(response->text[response->size]), ptr, size*nmemb);
  response->size += size*nmemb;
  response->text[response->size] = '\0';
  return size*nmemb;
}
void curl_request(CURL *curl, char *url, mem *response) {
  curl_easy_setopt(curl, CURLOPT_URL, url);
  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
  curl_easy_setopt(curl, CURLOPT_WRITEDATA, response);
  curl_easy_perform(curl);
}
char *build_url(char *cont) {
  char *url;
  if (cont) {
    int size = strlen(URL_BASE_CONT)+strlen(cont)+1;
    url = calloc(1, size);
    strncpy(url, URL_BASE_CONT, strlen(URL_BASE_CONT));
    strcat(url, cont);
  } else {
    url = malloc(strlen(URL_BASE)+1);
    strcpy(url, URL_BASE);
  }
  return url;
}
cJSON *parse_json(cJSON *json) {
  cJSON *pages;
  if (json) {
    pages = cJSON_GetObjectItem(json, "query");
    pages = cJSON_GetObjectItem(pages, "pages");
    pages = pages->child;
  }
  return pages;
}
char *get_cont(cJSON *json) {
  cJSON *jcont = cJSON_GetObjectItem(json, "query-continue");
  if (jcont && jcont->child->child) {
    char *cont = malloc(strlen(jcont->child->child->valuestring)+1);
    strcpy(cont, jcont->child->child->valuestring);
    return cont;
  } else {
    return NULL;
  }
}
page *fill_arrays(page *pag, int *i, cJSON *json) {
  cJSON *cur_page = json;
  page *pages = pag;
  do {
    pages = realloc(pages, *i*sizeof(page)+sizeof(page));
    if (json->child) {
      int size = strlen(cur_page->child->next->next->valuestring)-9;
      char *lang = malloc(size+1);
      strcpy(lang, cur_page->child->next->next->valuestring+9);
      pages[*i].name = lang;
    } else {
      pages[*i].name = "no name";
    }
    int task = cur_page->child->next->next->next?cur_page->child->next->next->next->child->valueint:0;
    pages[*i].num = task;
    *i = *i+1;
    cur_page = cur_page->next;
  } while (cur_page->next);
  return pages;
}
void sort_arrays(page *pages, int *size) {
  int sorted = 0;
  do {
    sorted = 1;
    for (int i = 0;i<*size-1;i++) {
      if (pages[i].num<pages[i+1].num) {
        sorted = 0;
        int a = pages[i+1].num;
        pages[i+1].num = pages[i].num;
        pages[i].num = a;
        char *s = pages[i+1].name;
        pages[i+1].name = pages[i].name;
        pages[i].name = s;
      }
    }
  } while (sorted!=1);
}